Upgrade test projects to net5.0

Fix compile errors on CS8073.
Fix tests on argument null exception message.

Author: angularsen

CodeGen/Generators/UnitsNetGen/UnitTestBaseClassGenerator.cs

@@ -371,7 +371,8 @@ public void EqualityOperators()
             var a = {_quantity.Name}.From{_baseUnit.PluralName}(1);
             var b = {_quantity.Name}.From{_baseUnit.PluralName}(2);
 
- // ReSharper disable EqualExpressionComparison
+#pragma warning disable CS8073
+// ReSharper disable EqualExpressionComparison
 
             Assert.True(a == a);
             Assert.False(a != a);
@@ -383,6 +384,7 @@ public void EqualityOperators()
             Assert.False(null == a);
 
 // ReSharper restore EqualExpressionComparison
+#pragma warning restore CS8073
         }}
 
         [Fact]

UnitsNet.NumberExtensions.Tests/UnitsNet.NumberExtensions.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.1</TargetFrameworks>
+    <TargetFrameworks>net5.0</TargetFrameworks>
     <RootNamespace>UnitsNet.NumberExtensions.Tests</RootNamespace>
     <LangVersion>latest</LangVersion>
     <IsTestProject>true</IsTestProject>

UnitsNet.Serialization.JsonNet.CompatibilityTests/UnitsNet.Serialization.JsonNet.CompatibilityTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.1</TargetFrameworks>
+    <TargetFrameworks>net5.0</TargetFrameworks>
     <RootNamespace>UnitsNet.Serialization.JsonNet.CompatibilityTests</RootNamespace>
     <LangVersion>latest</LangVersion>
     <IsTestProject>true</IsTestProject>

UnitsNet.Serialization.JsonNet.Tests/UnitsNet.Serialization.JsonNet.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.1</TargetFrameworks>
+    <TargetFrameworks>net5.0</TargetFrameworks>
     <RootNamespace>UnitsNet.Serialization.JsonNet.Tests</RootNamespace>
     <LangVersion>latest</LangVersion>
     <IsTestProject>true</IsTestProject>

UnitsNet.Serialization.JsonNet.Tests/UnitsNetBaseJsonConverterTest.cs

@@ -44,7 +44,7 @@ public void UnitsNetBaseJsonConverter_ConvertIQuantity_throws_ArgumentNullExcept
         {
             var result = Assert.Throws<ArgumentNullException>(() => _sut.Test_ConvertDoubleIQuantity(null));
 
-            Assert.Equal($"Value cannot be null.{Environment.NewLine}Parameter name: quantity", result.Message);
+            Assert.Equal("Value cannot be null. (Parameter 'quantity')", result.Message);
         }
 
         [Fact]

UnitsNet.Serialization.JsonNet.Tests/UnitsNetIComparableJsonConverterTest.cs

@@ -49,7 +49,7 @@ public void UnitsNetIComparableJsonConverter_ReadJson_throws_ArgumentNullExcepti
         {
             var exception = Assert.Throws<ArgumentNullException>(() => _sut.ReadJson(reader, typeof(IQuantity), null, false, serializer));
 
-            Assert.Equal($"Value cannot be null.{Environment.NewLine}Parameter name: {paramName}", exception.Message);
+            Assert.Equal($"Value cannot be null. (Parameter '{paramName}')", exception.Message);
         }
 
         [Fact]

UnitsNet.Serialization.JsonNet.Tests/UnitsNetIQuantityJsonConverterTest.cs

@@ -39,7 +39,7 @@ public void
         {
             var exception = Assert.Throws<ArgumentNullException>(() => _sut.WriteJson(writer, Power.FromWatts(10D), serializer));
 
-            Assert.Equal($"Value cannot be null.{Environment.NewLine}Parameter name: {parameterName}", exception.Message);
+            Assert.Equal($"Value cannot be null. (Parameter '{parameterName}')", exception.Message);
         }
 
         [Fact]
@@ -104,7 +104,7 @@ public void UnitsNetIQuantityJsonConverter_ReadJson_throws_ArgumentNullException
         {
             var exception = Assert.Throws<ArgumentNullException>(() => _sut.ReadJson(reader, typeof(IQuantity), null, false, serializer));
 
-            Assert.Equal($"Value cannot be null.{Environment.NewLine}Parameter name: {paramName}", exception.Message);
+            Assert.Equal($"Value cannot be null. (Parameter '{paramName}')", exception.Message);
         }
 
         [Fact]